The present invention relates to a yielding arrangement of a bumper at the body of a motor vehicle with impact-absorbing shock absorbers extending approximately in the driving direction, of which each is connected at one end with a bumper and is supported at the other end against an energy-dissipating deformation member arranged at the body.
Impact-absorbing shock absorbers are so designed in such arrangements--in some countries by reason of laws--that they absorb the entire impact energy up to an impact velocity of 8 km/h and then automatically regenerate themselves again. A large proportion of all frontal impact accidents, however, takes place at slightly higher impact velocities between 12 and 15 km/h. If the impact-absorbing shock absorbers are connected essentially rigidly with the body of the motor vehicle, such as with the longitudinal bearers thereof, greater damages occur at the body structures of the motor vehicles at the just-mentioned impact velocities. The repair expenditure can then be quite considerable.
In order to counteract this, it is already known (DE-OS No. 24 41 557) to support impact-absorbing shock absorbers at the longitudinal bearers of a motor vehicle by way of energy-dissipating elements. The impact-absorbing shock absorber protrudes for that purpose with one end into the interior space of the longitudinal bearer and is arranged with this end at a deformation member having a so-called honeycomb structure. The honeycomb structure can be compressed to a length of about 20% of the original length. It therefore requires more installation space than is available as deformation path in case of a load.
The present invention is concerned with the task to indicate an arrangement of a bumper at the body of a motor vehicle of the aforementioned type which also with constricted space conditions assures a comparatively large deformation path in the deformation member with as uniform as possible a deformation force and therefore with a high energy-absorption capacity.
The underlying problems are solved according to the present invention in an arrangement of a bumper at the body of a motor vehicle in that the deformation includes several roll sheet metal members which extend substantially parallel to the impact-absorbing shock absorber along the inner wall of a housing secured at the body and are connected at their ends opposite the bumper with the housing whereas the other ends are secured at the impact shock absorber. A roll sheet metal member is a relatively simple structural element. By its arrangement in the housing, an essentially constant bending radius in the roll area of the sheet metal member is assured in case of a displacement of the impact shock absorber within the same housing. As a result thereof, the deformation resistance is essentially the same over the entire deformation path and a far-reachingly rectangular force-displacement-diagram is obtained. With such a force curve, a high energy absorption capacity can be attained with a predetermined maximum force. If the end of the impact shock absorber which is connected with the roll sheet member is displaced up to the other end of the roll sheet member (in the original condition), then the roll sheet member has rolled off only up to the center thereof, from which follows that the utilizable deformation path is about twice as long as the leg length of the roll sheet member.
In a particularly preferred embodiment of the present invention, the housing is detachably connected with a longitudinal bearer of the body. In this manner, a damage of the front end structure, respectively, of the longitudinal bearer can be still avoided completely, for example, with impact velocities of about 8 to 12 km/h, whereby in the case of repairs, only the housing then has to be replaced by a new housing with not-yet deformed roll sheet members.
At somewhat higher impact velocities, the longitudinal bearer will also be deformed already in the forward area thereof; however, a large portion of the impact eergy has been absorbed beforehand by the impact shock absorber and the deformation member constructed according to the present invention so that it will be frequently possible to repair the engine bearer with a so-called cut-off repair, in which only a Part of the bearer--appropriately beginning with a suitable separating place--has to be replaced.